INSECTS AFFECTING PARK AND WOODLAND TREES 99 



Life history. Comparatively little has been published regarding the 

 life history of this insect. The beetles occur on the trunks and branches 

 of various poplars in August and September. The most obvious signs of 

 infestation are the numerous blackened, swollen scars on the trunk and 

 limbs. These are sometimes open and in early summer large quantities of 

 borings are expelled from the galleries and frequently occur in considerable 

 amounts about the base of the tree. This is very evident during the latter 

 part of May and in early June. Pupae were found in large numbers about 

 Alban)- in earl}- June, and adults appeared early the following month and 

 continued to emerge throughout July and were probably abroad during 

 August and into September. Full grown larvae were also met with in 

 early June, indicating that there was not much uniformity in the time of 

 pupation. The pupal stage probably lasts three or four weeks, and the 

 chamber where the final transformations take place, is invariably located 

 near the center of the smaller limbs and at some distance from the surface 

 in trunks. The top is smoothly excavated, the other end is closely packed 

 with coarse fibers which are attached at one end to the side of the galleries 

 and the portion next to the pupa is packed with much finer borings and 

 then coated with very fine sawdust. This pupal chamber is probably made 

 the previous season, but final transformations do not occur till spring. 

 The young larva works in the inner bark and outer sapwood for a short 

 time and before the approach of cold weather sinks its burrow to a greater 

 depth. The galleries of the second year are very largely in the interior 

 of the wood, and during this stage the limb or trunk may be honeycombed 

 with very large, somewhat irregular galleries. The nearly full grown 

 larvae not infrequently excavate large, .shallow galleries in the sapwood and 

 inner bark, and appear to subsist to a considerable extent on the sap 

 collected in such cavities. Three years are probably required to complete 

 the life cycle. 



Food plants. This species appears to infest practically all poplars, and 

 it has been recorded from the lombardy poplar, the cottonwood and the 

 common aspen besides other species or varieties. 



